The present invention generally relates to systems for displaying images on dome-shaped screens, and in particular, to human interface devices for use with such systems.
Numerous systems have been developed for displaying images on any of a variety of dome-shaped screens. For example, hemispherical screen display systems have commonly been used in planetariums and other immersive environments. Such displays are typically 180 degrees from their front, through their topmost or zenith point to their back, although many are built with screens that are less than or greater than 180 degrees.
Such display systems have recently migrated to digital technology, leading to the need for increased interactivity with the display. Traditional human interface devices (HID's) used to operate such digital systems have, in practice, been found to be very problematic in this environment. The problems associated with such devices, for example, a computer mouse, a graphics tablet or a trackball, can be separated into two categories.
First, traditional HID's typically operate in a planar coordinate system, whereas the dome display is better suited to a spherical coordinate system. In particular, it has been found that in practice, linear movements of a mouse, for example, will not naturally produce a corresponding movement of the cursor on a domed screen. As an example, the vertical movement of a mouse will naturally move the cursor on a flat display directly from the bottom to the top of the screen. On a hemispherical screen, however, similar vertical movement of a mouse will not typically translate to a straight line path of the cursor on the screen. As a result of this, an operator will quickly find themselves very disoriented in attempting to predict how inputs from a planar HID will translate into cursor movements on the domed screen.
Second, the curved surface of a dome display makes the incremental nature of most traditional HID's problematic. On a flat screen, cursor movements shown when a user moves an HID device correspond naturally to the user's frame of reference. When a normally flat image is curved onto a dome, however, this correspondence is lost so that, for example, a movement of the HID from left to right might become a movement on the display from right to left, depending on the cursor's location on the screen.
In order for the user to place the cursor in a desired location, the user must first know the cursor's current location to determine which way to move it. This is easy to determine with a traditional computer monitor, having a substantially flat display, but much more difficult with a dome display system that is radically different from the user's frame of reference. Put simply, it is very easy on a dome display to lose track of the cursor's location. Digitizer tablets do provide a rigid mapping between the pen position and the cursor position on the display, which is helpful. However, the size and shape of the digitizer tablet still makes it very difficult for a user to translate a position on the tablet to a position on the domed screen.